Controlled generator



Oct. 25, 1949. R. w. CLARK 2,486,005

CONTROLLED GENERATOR Filed Feb. 26, 1946 F 92 L21! "e0 r l N V E N TO R MaMMr/m Merl/l.

Ill/P07 BY ATTORN EY Patented Oct. 25, 1949 UNITED STATES PATENT. OFFICE CONTROLLED GENERATOR Robert W. Clark, Teaneck, N. J., assignor to Radio Corporation of America, a corporation of Dela- Application February 26, 1946, Serial No. 650,373

4 Claims. (Cl. see-.28)

This application relates to oscillation. generators and to control circuits therefor, and in particular to ultra high frequency generators and reactance tube modulators therefor wherein a wide frequency range or band of modulating potentials may be used.

The general object of the present invention is to improve ultra high frequency generators and particularly to provide an ultra high frequency generator the frequency of which may be varied through a wide range of frequencies.

A further object of the present invention is to improve frequency determining circuits in ultra high frequency generators used in timing modulation and similar systems, and in particular to providea frequency determining circuit in a generator wherein the ratio AF/] is high (where AF equals carrier deviation, and f equals highest modulation frequency).

A further object of the present invention is an improved voltage phasing network for deriving the phase quadrature voltage for the reactance tube control grid in ultra high frequency timing modulation systems.

The manner in which the above objects are attained will now be described. In this description reference will be made to the attached drawings wherein Figs. 1, 3 and 5 are :basic circuit diagrams used in illustrating the novel features. of my ultra high frequency generator and phasing network; Figs. 2 and 4 are vector diagrams used in explaining the operation of the circuits 2 across the circuit including inductance Ll, Cl, and induced therefrom to the circuit including condenser C2 and inductance L2; the relation of I the currents and voltages will be as represented by the vector diagram in Fig. 4. The voltage of frequency F induced in the circuit containing L2 and C2 may be considered the same as e0, in Fig. 1, which is an equivalent circuit. Thus all is effectively in series with the inductance L2 and therefor will now be described with reference to Figs. 5 and 6 of the drawings. As shown in of Figs. 1, 3 and 5; while Fig. 6 shows schematically and by circuit element and circuit connection the essential features of a reactance tube timing modulated oscillator generator arranged in accordance with my invention.

The nature of operation of the circuit may be described by starting with the basic circuit diagram of Fig. 1. When the frequency F of a generator ell is the same as the series resonant frequency of inductance L2 and condenser C2 then the current i2 is in phase with the voltage c0, and the voltage e2 across the condenser C2 will be 90 out of phase with respect to the voltage ell. This voltage relation is shown by the vectors in Fig. 2 of the drawings. In' the diagram of Fig. 1 the resistor R will be referred to hereinafter as a damping resistor. and this resistor serves to broaden the frequency versus voltage characteristic of the seriesresonant circuit.

If two circuits such as illustrated in Fig. 3 tuned to the same frequency are mutually coupled and voltage or energy cl "of the frequency F to which the circuits are tuned is supplied as shown Fig. 5 the capacitancesCi and C2 may be divided. Then the capacitance C2 of Fig. 3 may be comprised of capacitances Cl i' and CH of Fig. 5. The

capacitance Cll may be the series tuning condenser in the reactance tube phasing network, and the capacitance Cl! may represent the fixed capacity between the grid and cathode of the' reactance tube and distributed circuit capacities. The voltage e2 then is in quadrature with the voltage el which may be the voltage developed between the anode and cathode of the oscillation generating tube. ,The capacitance CI of Fig. 3 is comprised of three capacitances represented by C3, C4 and C5. Of these, capacitance C! may represent the capacity between the'anodes and ground of both sections of the tube 25 of Fig. 6. The capacitance C4 may represent the capacity within the oscillatorsectioh of the tube between the control grid and ground. The capacitance C6 is the variable tuning capacitor and since it is in series with C4 the parallel resonant circuit operates at a higher frequency.

Cl and Cl! are the normal tube capacities. If C5 and CH are of the same order of magnitude as Cland CH respectively, the shunting effect of the tube capacities is reduced and the circuit will operate at a higher frequency than normally. I make the value of capacitance C! approximately equal to or less than that of C4. CH and CH similarly are of substantially equal values. Under these conditions the capacitors C5 and Cl I, if variable, may be used to tune the circuits to the desired frequency F. Thus variation of C5 or CH mutually changes the tuning of the circuit and thus the circuits may be operated at higher parallel and series frequencies respectively. Furthermore, with these series condenser arrangements larger inductances may be used for a given frequency, which results in increasing the frequency deviation obtainable. Thus my system permits a wide deviation in frequency at a carrier frequency not usually obtainable with lumped circuit elements.

Au embodiment of a timing modulation generator of the reactance tube type is illustrated mm. 6. InFig.6 asingletube28.ofsaytype 829, has two sections, one of which includes 1 anode 8, positive grid electrode 9, control grid 1, and cathode 8, regeneratively coupled in an oscillation generating circuit including inductance Li and series condenser C8, connected between the anode 8 and grid 1. C4 represents the grid to ground tube capacity while I8 is a biasing resistor for the control grid 1. The high frequency oscillation generating circuit is completed by resistor 24 connected to a point on LI and to the positive terminal of a source of direct current shunted by a bypassing condenser 88. The resistor 24 allows inductance Ll to sein series with a capacitor C and resistor I3, is

connected between control grid l6 and ground. The circuit is as a consequence effectively in shunt to the capacitor C|2 between the control grid l5 and cathode it.

Due to the mutual inductance M between the inductances Li and L2, voltage is induced in inductance L2, which produces a current through inductance L2, capacitor C, resistor l3 and capacitor Cl2. When this circuit is tuned to resonance the voltage across capacitor Ol2 is in phase quadrature with the voltage on anode 8.

The voltage across capacitor (H2 is applied between the control grid i5 and the electron emitter or cathode M of this section of the tube.

' 1 The anode it of this-section of the tube is connected substantially directly to the, anode 8 of the oscillation generator section so that both anodes operate at high frequency voltages of the same phase. Current flow through the reactance tube section is normally in phase with the voltage 5 on the control grid l5 so that the current through the reactance tube section is in phase quadrature with respect to the voltage on the anodes 8 and I8, thereby producing a reactive effect in the oscillation generator section. The resistance I2 is, as described hereinbeforaa damping resistor. Modulation is applied to control grid I5 through resistor 18, which isolates the capacitor C|2 from the capacity to ground of the modulator circuit 20. This circuit 20 is generally one suitable for television signals, but may be changed if signals other than television are to be used. The modulator 20 comprises'a tube 28 having its control grid 21 excited by modulating potentials and having its anode 28 coupled to the reactance tube 5 by a video peaking circuit including condenser 32 and inductances 34 and 38, and resistors 88 and 48. The network is one that will give max-v imum band width for maximum gain, and its combination of values is well known in the art. 7 means for increasing the fr q n y to which The advantages claimed are that with this type of tuning, the inductances are larger than if parallel tuning of a different kind were used, so with lumped inductances the circuit may be in which the inductive and capacitive reactauces are made equal. Au 829 tube performed satisfactoriiy at 158 megacycles, and it could operate satisfactorily at a higher frequency.

What is claimed is:

1. A simulated reactance comprising an electron discharge tube having a cathode, an anode-' like electrode and a control grid, means for producing a reactive effect between said anode-like electrode and said cathode including a tuned circuit having a plurality of reactances, two of which are capacitive and of about like value in series, one of said capacitive reactances including the reactance between the control grid and cathode of said tube, said tuned circuit having inductive reactance equal in value to and in paral-.

lel circuit with the capacitive reactance thereof, a coupling between the tuned circuit and the anode-like electrode, and means for setting up oscillatory energy of frequency F in said tuned circuit.

2. A simulated reactance comprising an electron discharge tube havmg a cathode, an anodelike electrode and a control grid, means for pro- 25 duclng a reactive eilect between said anode-like electrode and said cathode including. an inductor and two series connected capacitors of about like value in parallel with said'inductor in a circuit tuned to a frequency F, one of said capacitors including the reactance between the control grid and cathode of said tube, a coupling between the inductor of said tuned circuit and the anodelike electrode, and means for setting up oscillatory energy of frequency F in said tuned circul 3. Ina timing modulation system, a high frequency 080111313021 generator comprising an electron discharge device having an anode, a cathode and a control grid regeneratively coupled by a tank circuit parallel tuned to a frequency F by a -reactance including an inductor and the capacitance between the control grid and cathode and between the anode and'cathode, means for increasing the frequency to which said circuit is parallel tuned comprising a variable capacitor in series with the reactance of said parallel tuned circuit, means for modulating the timing of the .oscillations generated through a wide range comprising a reactance tube having an anode, a cathode and a control grid, connections tying the anode of the reactance tube to the anode of the first named device, a second parallel circuit tuned to said frequency F including an inductor and a capacitor in series with the capacitance between the cathode of said reactance tube and the control grid of said reactance tube, there being mutual coupling between said last named inductor and the inductor of said first parallel tuned circuit, and means for modulating the conducoo tivity of said reactance tube in accordance with 4. In a wide band frequency modulation system, a high frequency oscillation generator comprising an electron discharge device having an anode, a cathode and a control grid regeneratively coupled by a tank circuit parallel tuned to a frequency F by a reactance including an inductor and the capacitance between the control grid and cathode and between the anode and cathsaid circuit is parallel tuned comprising a variable capacitor in series with the reactance of said parallel tuned circuit, means for modulating the frequency of the oscillations generated used at higher frequencies. The tuning is that through a wide range comprising a reactance 6 tube having an anode, a cathode and a oton- REFERENCES CITED trot grid. 11 second circuit tuned to the said requency 1'' comprising an inductor, a variable tunt iiggw igg of "cord in in: capacitor and the capacitance between the pa control grid and cathode of aid reaetance tube, UNITED STATES PATENTS a coupling between said inductors, a direct con- 5 nection between the anode: of said tube and said g? g device, and means for modulating the conduc- 2182377 Gmmen; Dec

tivity of said reaotance tube in accordan e with 212781129 Crosby 1' magic]: cover a relatively wide range of N 2323598 Hathaway July 6 w m I 2,422,422 Korman June 17, 1M! 

